Description
Shytomel (Liothyronine) 5 mcg
Shytomel 5 mcg is identified as a liothyronine sodium tablet. Liothyronine is a synthetic thyroid hormone used to replace or supplement thyroid hormone when the body does not produce enough on its own. Official prescribing information for liothyronine tablets describes it as a prescription thyroid hormone product for oral use.
Active Ingredient and Medicine Class
The verified active ingredient is liothyronine sodium, also known as triiodothyronine (T3). It is a synthetic thyroid hormone and belongs to the thyroid hormone replacement class.
Established Medical Uses
Liothyronine is established for the treatment of hypothyroidism. Prescribing information also includes use in thyroid hormone suppression settings such as pituitary TSH suppression. Clinical guidance notes that liothyronine is generally not first-line for routine hypothyroidism replacement, and that any use alongside levothyroxine should be considered selectively in carefully assessed patients.
How It Works
Liothyronine replaces the active thyroid hormone T3. Thyroid hormones help regulate metabolism, energy use, growth, and many body functions. Because liothyronine is the active hormone form, it acts more directly than levothyroxine, which must be converted by the body into T3.
Important Safety Information
Liothyronine should be used cautiously in people with cardiovascular disease because excess thyroid hormone can increase heart rate and cardiac workload. It is also important to avoid over-replacement, which can produce symptoms of hyperthyroidism and long-term risks such as bone loss or heart rhythm problems. Prescribing information highlights clinically significant interactions with medicines and factors that affect thyroid hormone levels or absorption, including drugs that alter thyroid hormone pharmacokinetics.
Published guidance also emphasises that persistent symptoms alone do not prove a need for liothyronine, and that treatment decisions should be individualized and based on confirmed overt hypothyroidism and clinical assessment.
Possible Side Effects
Common adverse effects of excess thyroid hormone may include palpitations, nervousness, tremor, insomnia, sweating, heat intolerance, and weight loss. More serious reactions can include arrhythmias, worsening angina, and other manifestations of thyrotoxicosis.
Scientific Evidence
Peer-reviewed reviews and consensus statements report that randomized trials have generally not shown clear benefit of levothyroxine-liothyronine combination therapy over levothyroxine alone for most patients with hypothyroidism. More recent systematic review evidence continues to describe uncertainty about long-term safety and overall comparative benefit, which is why liothyronine use remains selective rather than routine.
Medical Information Notice
This summary is for educational purposes only and is based on sources available at the time of review. It does not replace the official patient leaflet, prescribing information, or assessment by a qualified healthcare professional.
Medical Sources
- DailyMed: Liothyronine Sodium tablet prescribing information. View source
- FDA: Cytomel (liothyronine sodium) tablets, prescribing information. View source
- Ahluwalia R, et al. Use of liothyronine (T3) in hypothyroidism: Joint British Thyroid Association/Society for endocrinology consensus statement. Clinical Endocrinology (2023). View PubMed article
